I am no more saying that there was a fire in the cabin, than I am saying was no fire in the cabin. It is just that this point, it cannot be taken for granted.
Lemishko said witnesses saw a flash of some kind coming from the helicopter before it started to descend. The NTSB is looking into anything that could have caused the a flash to come from the aircraft, but said that the flash is just "one small piece of the puzzle."
In one accident report I studied at the NTSB school, a "flash" was observed coming from the aircraft just prior to impact. The flash turned out to be the strobe light.
Sometimes if one places too much importance on an eyewitness report, other factors can be overlooked. There are eyewitnesses that have not a clue about aircraft, then there are eyewitnesses that are professionals in aviation. Unfortunately usually it is the former that witness the vast majority of aircraft accidents.